Filter device and filter element

ABSTRACT

A filter device comprising a filter element ( 9 ), which can be received in a housing ( 1 ) that can be closed by means of a cover part ( 3 ) having fluid ducts ( 35, 41 ), a connecting unit being provided in order to create a fluid-conducting connection between the filter element ( 9 ) and an associated fluid duct ( 35 ) of the cover part ( 3 ), is characterized in that the connecting unit is configured in the form of a coupling having a movable coupling part ( 33 ), which in the functional state creates the fluid-conducting connection.

The invention relates to a filter device with a filter element, which can be received in a housing that can be closed by means of a cover part that has fluid ducts, there being a connecting unit for forming a fluid-conducting connection between the filter element and an associated fluid duct of the cover part. The invention furthermore relates to a filter element that is intended for the filter device.

Filter devices for receiving filter elements are readily available on the market in a plurality of embodiments; compare, for example, EP 1 287 871 A1 or EP 0 891 214 B1. A not insignificant portion of the production costs in these filter devices originates from the formation of the connecting unit which, in the operating state in which the filtration process can take place, establishes a suitable connection between the filter element and the respectively associated fluid duct in the cover part. On the one hand, the connecting unit must be designed such that the installation processes for changing the filter elements are made simple and uncomplicated, but that, on the other hand, reliable sealing occurs, even at high pressure levels. Moreover, the connecting unit, as much as possible, should be made such that in the operation of the filter device there is “replacement reliability”. In other words, a construction is desirable in which in view of the plurality of designs in which there are filter elements on the market, it is ensured that only in uses of these filter elements, which are specially adapted to the housing and the cover part, can an operating state be achieved, so that the risk that filter elements of an unintended type with unsuitable filter properties will be inadvertently operated is avoided.

With respect to this problem, the object of the invention is to make available a filter device in which the connecting unit meets the requirements which are to be imposed to a significant extent.

According to the invention, this object is achieved by a filter device having the features of claim 1 in its entirety.

Accordingly, one particularity of the invention consists in that the connecting unit is formed by a type of coupling, a movable coupling part in the operating state of the device establishing the fluid-conducting connection between the filter element and the associated fluid duct of the cover part, i.e., assumes a coupling position in the operating state. In this way, not only can a fluid connection be implemented which forms perfect sealing, but it also becomes possible by corresponding construction of the filter housing, especially its cover part, to ensure that the device can only be put into the operating state when a filter element is used in whose installation in the housing the movable coupling part of the connecting unit can assume its operating or coupling position.

Preferably, the arrangement is such that the coupling part can be axially moved and adjoins the coupling part of the connecting unit, which part is arranged stationary, in the operating state by spring pretensioning with the formation of a seal. This especially advantageously makes it possible to design the connecting unit to be as it were “self-controlling”, specifically such that attachment of the cover part to the housing leads directly to elastic contact of the axially movable coupling part with the associated stationary coupling part.

Especially advantageously, the arrangement is such that there is a movable coupling part on the filter element and the stationary coupling part is on the cover part and is formed by the mouth edge of the associated fluid duct. The direct interaction between the movable coupling part and mouth edge of the fluid duct leads to an especially simple and compact construction.

The element-side movable coupling part can be advantageously formed by a sleeve body which forms a fluid passage from the filter cavity which is coaxial to the longitudinal axis and which is surrounded by a filter medium toward the associated fluid duct of the cover part.

In this respect, the sleeve body on the outer peripheral side can be displaceably guided with the formation of a seal in a duct which is connected to the end cap of the filter element so that the sleeve body performs both a coupling function and also establishes a direct fluid passage between the fluid duct of the cover part and the inner filter cavity of the filter element which is conventionally bordered by a tubular, fluid-permeable support body which is in turn surrounded by a filter medium. In this connection, the duct of the sleeve body can form an extension of the end of the support body adjacent to the end cap so that the sleeve body forms a coaxial extension of the filter cavity.

Advantageously, the coupling here can be made such that the mouth edge of the associated fluid duct which forms the stationary, cover-side coupling part defines a seal plane against which the sleeve end edge of the sleeve body which forms the movable coupling part can be pressed to form an axial seal by spring pretensioning, as a result of which an especially compact construction of the coupling arises.

In this configuration, on the mouth edge of the cover-side fluid duct and on the sleeve end edge of the sleeve body, sealing edges and/or sealing surfaces which interact with one another can form the axial seal.

In especially advantageous embodiments, the axial seal can be made such that the sleeve end edge and the mouth edge each form a ring surface, one ring surface being made as a continuous radial plane and the respective other ring surface being made as a radial plane with a sealing edge that projects slightly out of it. This results in especially good sealing so that operating reliability is ensured even at high pressure levels.

Especially advantageously, the arrangement here can be made such that the sealing edge is located annularly on the outer periphery of a ring surface such that it encloses the outer periphery of the other ring surface as a centering element. This ensures that when the cover part is attached, an extremely precise, flush alignment of the coupling parts occurs even if components on the side of the filter element, such as the end cap, support body, and the like, as injection moldings of plastic material are subject to tolerances since the centering formed on the sealing surfaces also ensures in this case exact alignment and thus the desired seal properties.

The subject matter of the invention is also a filter element for a filter device according to one of claims 1 to 11, the filter element having the features of claim 12 in its entirety.

The invention is detailed below using embodiments shown in the drawings.

FIG. 1 shows a longitudinal section of one embodiment of the filter device according to the invention, drawn schematically simplified and on a slightly reduced scale compared to a practical embodiment;

FIG. 2 shows a longitudinal section which corresponds to FIG. 1, but according to the cutting plane indicated by II-II in FIG. 1;

FIG. 3 shows a conversely greatly enlarged partial section which shows only the head part from FIG. 2, and

FIG. 4 shows a perspective cutaway partial section of only the upper region of a modified embodiment of the filter device, which region is shown in FIG. 3, which section is more greatly enlarged compared to FIG. 3.

A cup-shaped filter housing 1, which is largely circularly cylindrical and which is closed on the bottom, on its upper end can be closed by a cover part 3 which can be detachably joined to the housing 1 via a screw connection 5. The cover part 3 in the head region has pockets 7 as encapsulated bore shoulders for a fouling display (not shown). The housing 1 can receive a filter element 9 which in a conventional design has a hollow cylindrical filter medium 11, for example in the form of layers of filter mat or a multilayer, folded, or pleated filter body which surrounds a tubular support body 13 which is injection molded from plastic material. The support body, as is most apparent in FIG. 4, has a succession of peripheral circular rings 15 which are spaced apart from one another, of which only a few are numbered in the figures, and which in the manner which is conventional for these support bodies 13 are connected to a carrier which is located inside and which is made as a star which is three-pointed in cross section, with three points 17. On the end associated with the bottom of the cup of the housing 1, the filter element 9 is closed by a bottom cap 19 of plastic material which forms an enclosure 21 for the filter medium 11. On the opposite end an end cap 23, which is likewise formed from plastic material, forms the termination of the filter element 9 facing the cover part 3, the end cap 23, in a similar manner as the bottom cap 19, forming an enclosure 25 for the pertinent end of the filter medium 11.

As can be taken most clearly from FIGS. 3 and 4, on the radially inside region of the enclosure 25 there is a hollow body 27 which together with an extension 29 which projects axially on the radially inside end of the end cap 23 in the direction to the cover part 3 forms a circularly cylindrical guide 31 in which a sleeve body 33 is guided to be axially displaceable, between the hollow body 27 and the extension 29 a seat being formed for a sealing element 32 which seals the sleeve body 33 relative to the duct 31. The sleeve body 33 is used as a movable coupling part of a connecting unit for producing a fluid connection between the filter element 9 and the fluid duct 35 in the cover part 3.

As can be taken from FIG. 1, the fluid duct 35 in the cover part 3 is connected to the fluid outlet 37 for the cleaned fluid. A fluid inlet 39 which is located in the cover part 3 opposite the latter for the fluid to be cleaned is connected in the cover part 3 to a second fluid duct 41, from which the fluid to be cleaned can flow via inflow openings 43 made in the end cap 23 into the annulus 45, which on the outside of the filter medium 11 forms the contaminated side of the filter device, from where the fluid to be cleaned passes through the filter medium 11 from the outside to the inside and reaches the inner filter cavity 47 which forms the clean side. From the inner filter cavity 47 the cleaned fluid travels through the sleeve body 33 which forms the coupling part of the connecting unit to the fluid duct 35 of the cover part 3 and thus to the fluid outlet 37.

The end cap 23, which is in a sealed connection both to the cup-shaped housing 1 and also to the cover part 3 on the outer peripheral side by way of a seal arrangement 49, is pressed against the housing 1 when the cover part is screwed onto the housing 1 by means of an inner collar 51 of the cover part 3. While the seal arrangement is formed in the embodiment of FIGS. 1 to 3 by a ring seal in the form of an O-ring 53, in the example shown in FIG. 4, instead on the outer periphery of the end cap 23, a dovetail-shaped flange ring 55 is formed on which a profile seal 57 is secured which has two lips 59, which are opposite one another in the axial direction and which each form their own sealing region relative to the cover part 3 and relative to the housing 1. Otherwise, the embodiment from FIG. 4 corresponds to the embodiment as shown in FIGS. 1 to 3 so that for a description of the details of the connecting unit, reference can be made both to FIGS. 1 to 3 and also to FIG. 4.

As already mentioned, as the movable coupling part a sleeve body 33 is guided to be axially displaceable within the duct 31. The hollow body 27, which is connected to the end cap 23 and which forms a part of the duct 31, on its inner end region has a shape which projects radially inward and which forms a stop shoulder 61 on which one end of a helical compression spring 63 is supported, said spring being supported within the sleeve body 33, adjoining its inside ribs 65 (only a few being numbered in FIG. 3) and with its other end on the inner ring shoulder 67 of the sleeve body 33. For the sleeve body 33 this yields pretensioning of the spring for axial motion which runs in the direction to the cover part 3. To limit this motion in the end position, on the extension 29 which forms part of the duct 31, there is a step 69 which constricts the duct and which interacts with a step 70 on the outer periphery of the sleeve body 33 for limiting the end position. All the figures which depict the operating state of the filter device show that when the cover part 3 has been screwed on, the sleeve body 33 is pushed out of the end position against the pretensioning of the compression spring 63 axially into the filter element 9. This is due to the mouth edge 71 of the cover-side fluid duct 35, as the stationary coupling part of the connecting unit for forming the coupling connection when the cover part 3 is screwed tight, pressing on the sleeve end edge 73 of the sleeve body 33 and pushing it out of the end position, so that the pretensioning of the compression spring 63 is active as a sealing force between the mouth edge 71 of the fluid duct 35 and the sleeve end edge 73 of the sleeve body 33. In other words, the coupling connection of the connecting unit is automatically established when the device is shifted into the operating state by screwing the cover part 3 onto the housing 1 which contains the pertinent filter element 9.

The interacting regions of the sleeve body 33 and the fluid duct 35, which in the coupling state form the seal arrangement, are designed such that one of the annular surfaces, which are pressed against one another by the pretensioning of the spring, forms a continuous radial plane, while the other ring surface forms a radial plane with a sealing edge which projects out of it. In these embodiments, the ring surface 75 on the fluid duct 35 is continuously level, while the ring surface 77 along its peripheral edge forms a slightly projecting sealing edge 79. The latter, with the radially outer edge of the ring surface 75, forms a seal not only in interaction with its surface edge, but by the edge enclosure of the mouth edge 71 of the fluid duct 35 also forms centering by means of which it is ensured that extremely precise alignment of the coupling connection of the connecting unit necessarily takes place when the cover part 3 is screwed on. Considering that the filter element 9, aside from the compression spring 63, can be made without metal, so that mechanical or thermal effects could lead to slight deformations, this centering constitutes an extremely advantageous contribution to the operating reliability of the device. 

1. A filter device with a filter element (9), which can be received in a housing (1) that can be closed by means of a cover part (3) that has fluid ducts (35, 41), there being a connecting unit for forming a fluid-conducting connection between the filter element (9) and the associated fluid duct (35) of the cover part (3), characterized in that the connecting unit is formed in the form of a coupling with a movable coupling part (33), which in the operating state establishes the fluid-conducting connection.
 2. The filter device according to claim 1, characterized in that the coupling part can be axially moved and adjoins the coupling part (71) of the connecting unit, which part is arranged stationary, in the operating state by spring pretensioning (63) with the formation of a seal.
 3. The filter device according to claim 2, characterized in that there is a movable coupling part (33) on the filter element (9) and the stationary coupling part is on the cover part (3) and is formed by the mouth edge (71) of the associated fluid duct (35).
 4. The filter device according to claim 3, characterized in that the element-side movable coupling part is formed by a sleeve body (33) which forms a fluid passage from the filter cavity (47), which is coaxial to the longitudinal axis and which is surrounded by a filter medium (11), toward the associated fluid duct (35) of the cover part (3).
 5. The filter device according to claim 4, characterized in that the sleeve body (33) on the outer peripheral side is displaceably guided with the formation of a seal in a duct (31) which is connected to the end cap (23) of the filter element (9).
 6. The filter device according to claim 5, characterized in that the mouth edge (71) of the associated fluid duct (35), which forms the stationary, cover-side coupling part, defines a seal plane (77) against which the sleeve end edge (73) of the sleeve body (33) which forms the movable coupling part can be pressed to form an axial seal by spring pretensioning.
 7. The filter device according to claim 6, characterized in that on the mouth edge (71) of the cover-side fluid duct (35) and on the sleeve end edge (73) of the sleeve body (33) sealing edges (79) and/or sealing surfaces (75, 77), which interact with one another, form the axial seal.
 8. The filter device according to claim 7, characterized in that the axial seal is made such that the sleeve end edge (73) and the mouth edge (71) each form a ring surface (75, 77), one ring surface (75) being made as a continuous radial plane and the respective other ring surface (77) being made as a radial plane with a sealing edge (79) that projects slightly out of it.
 9. The filter device according to claim 8, characterized in that the sealing edge (79) is located annularly on the outer periphery of one ring surface (77) such that it encloses the outer periphery of the other ring surface (75) as a centering element.
 10. The filter device according to claim 5, characterized in that the duct (31) of the sleeve body (33) in the end cap (23) has a step (69) which constricts the duct and which, with a step (70) on the outer periphery of the sleeve body (33), limits its motion in the direction to the cover-side coupling part against spring pretensioning in the end position.
 11. The filter device according to claim 10, characterized in that the sleeve body (33) has an inner ring shoulder (67) on which one end of a compression spring (63) which is located in the sleeve body (33) is supported, whose other end is supported on a stationary stop shoulder (61) of the guide (31).
 12. A filter element for a filter device according to claim 1, which can be received in a housing (1) that can be closed by means of a cover part (3) that has fluid ducts (35, 41), characterized in that, in the operating state, it can be moved into a fluid connection to an associated fluid duct (35) of the cover part (3) by means of a movable connecting unit (33) which is made in the form of a coupling. 